Microsoft researcher Eric Horvitz experienced one of those robot encounters we all dread. He was stuck in an elevator at Stanford Hospital when a droid the size of a washing machine 'whirled around' and almost knocked him down. Then he thought: 'What if I were a patient? There could be big issues here.'

Now Horvitz and other scientists and academics are starting to think about the implications. 'It is part of being a responsible scientist," Horvitz said.